A fuel supply pump, which pressurizes fuel to a high pressure of some hundreds of megapascals (MPa), has been known. Such a fuel supply pump is used to supply the fuel to an internal combustion engine through an accumulator (e.g., a common rail).
One such a fuel supply pump includes a high pressure pump and a tappet. In the high pressure pump, a plunger is axially reciprocated to draw fuel into a pressurizing chamber and to discharge the drawn pressurized fuel from the pressurizing chamber. The tappet converts rotation of a cam into linear reciprocation to axially reciprocate the plunger. Furthermore, the tappet includes a roller, a shoe and a tappet body. The roller reciprocates in the axial direction of the plunger while rotating about a rotational axis of the roller in response to the rotation of the cam. The shoe rotatably supports an outer peripheral surface of the roller. The tappet body holds the roller and the shoe and reciprocates in the axial direction of the plunger. Furthermore, the pump housing slidably supports the tappet body such that the pump housing holds the tappet in a manner that enables axial reciprocation of the plunger.
In order to reduce the weight of the tappet and limit rotation of the shoe, a fuel supply pump, which is disclosed in, for example, EP1413749A2, may be provided.
Specifically, in the fuel supply pump of EP1413749A2, the tappet includes a roller and a shoe. The shoe is configured into a quadrangular prism form. Furthermore, a tappet support member is press-fitted into the pump housing. The tappet support member supports the tappet to enable reciprocation of the tappet in the axial direction of the plunger. A quadrangular prism shaped slide hole, which slidably supports the shoe, extends through the tappet support member in the axial direction of the plunger. The pump housing slidably supports the shoe through the tappet support member such that the pump housing holds the tappet in a manner that enables axial reciprocation of the plunger.
Thereby, in the fuel supply pump of EP1413749A2, the tappet body is eliminated from the tappet to reduce the weight of the tappet, and rotation of the shoe is limited by configuring each of the shoe and the slide hole into the quadrangular prism form.
However, in the fuel supply pump of EP1413749A2, the press-fitting of the tappet support member into the pump housing may cause distortion of the slide surfaces of the slide hole of the tappet support member. Therefore, the reprocessing of the slide hole after the press-fitting of the tappet support member may be required.